Magn 4445 ZeroTouch migrations

This pull request is for MAGN-4445, ability to provide node name change upgrade information to ZeroTouch library developers.

A migration file is specified as an XML file in the same directory as the ZeroTouch library, with the same base name and ".Migrations.xml" appended. Here is an example migrations file:

```
<?xml version="1.0"?>
<migrations>
  <priorNameHint>
    <oldName>Autodesk.DesignScript.Geometry.Geometry.GetClosestPoint</oldName>
    <newName>Autodesk.DesignScript.Geometry.Geometry.ClosestPointTo</newName>
  </priorNameHint>
  <priorNameHint>
    <oldName>Autodesk.DesignScript.Geometry.PolySurface.ProjectCurve</oldName>
    <newName>Autodesk.DesignScript.Geometry.Surface.ProjectInputOnto</newName>
  </priorNameHint>

</migrations>
```

When loading a ZeroTouch library, this migrations file is searched for, parsed, and stored in LibraryServices. When loading the Dynamo graph xml file, LibrarySevices is queried for any name changes.

@ikeough